* {
  margin: 0;
  padding: 0;
}

.cow-demo-box {
  width: 100vw;
  height: 100vh;
  background-image: url('./bg.jpg');
  background-size: 100% 100%;
  position: relative;
}

.cow-box {
  position: absolute;
  left: 100px;
  top: 100px;
  opacity: 0;
  transition: opacity .3s linear;
}

.cow-box-image {
  width: 200px;
  height: 200px;
  position: absolute;
  left: -100px;
  top: -100px;
}

.begin-btn {
  position: fixed;
  left: calc(50vw - 50px);
  bottom: 100px;
  width: 100px;
  height: 100px;
  background-image: url('./puase.png');
  background-size: 100% 100%;
}